RAMI4ATM phase
In RAMI4ATM each individual experiment is identified, as in the previous RAMI-V phase, as a combination of a test case and a measurement.
As schematized in Figure 1, each test case originates from the combination of a specific scenario, which describes the coupled surface/atmosphere system, a spectral band (<BND>) and the geometry of illumination (<zZZaAAA>).
Each participant is asked to identify submitted output files with the _<model> tag.
The filename is case sensitive, hence upper and lower letters should be used as they appear in the template of Figure 1.
The <model> tag is the user's model name.
It should be composed of a maximum of 20 characters (including [a-b][0-9] - ).
It is encouraged to use a meaningful name including at least a reference to your team.
For instance, to distinguish different submission of the same model as operated by different users, the system will accept model names such as, model1-team1. Furthermore, in case team1 would use model1 in a different configuration (to be specified in the "note" field), a suitable model name would then be model1-team1-version1.
Here is a non-exhaustive list of information that users are advised to include in the note field during the model registration (note: this is editable even after the model registration):
Some examples of valid filenames are given below:
This page lists all the information needed to perform the experiments defined by RAMI4ATM. The information to setup each individual experiment listed by the file RAMI4ATM experiments names, can be obtained from each section listed in the left menu, or by scanning the RAMI4ATM experiments description JSON file, described in the following section.
The surface identifiers in the experiment filenames are HOM00_LAM, HOM00_BLA, HOM00_WHI, HOM00_RPV, HOM00_RLI (for surfaces without the canopy component), and HOM25_LAM, HOM35_LAM, HOM45_LAM (for the homogeneous canopies with Planophile, Erectophile and Uniform LAD, respectively).
<HOMxx>_<SUR> identifier tag | Surface description |
---|---|
HOM00_LAM | Lambertian |
HOM00_BLA | Black Lambertian |
HOM00_WHI | White Lambertian |
HOM00_RPV | Anisotropic RPV |
HOM00_RLI | Anisotropic Ross-Li |
HOM25_LAM | Homegeneous Discrete Canopy (with Planophile LAD) with Lambertian background |
HOM35_LAM | Homegeneous Discrete Canopy (with Erectophile LAD) with Lambertian background |
HOM45_LAM | Homegeneous Discrete Canopy (with Uniform LAD) with Lambertian background |
<MAΤP> tag is used to describe the atmosphere. It is composed of 4 alphanumerical codes representing the molecular scattering and/or absorption (M), the aerosol type (A), the aerosol optical thickness at 550 nm (Τ), and finally the atmospheric profile (P) which can be rescaled accordingly to different values of water vapour and ozone. Table 12 shows the possible values for each of the <MAΤP> codes. It should be pointed out here that in RAMI4ATM consider only a subset of all the possible combinations of the four codes.
Molecules | Aerosols | Aerosol optical thickness | Molecular rescaling profiles | |||
---|---|---|---|---|---|---|
#1 char |
#2 char |
#3 char |
Priority | #4 char |
Priority |
|
|
|
|
---|
Ozone\WV/th> | Low | Standard | High |
---|---|---|---|
Low | - | L | - |
Standard | D | S | W |
High | - | O | H |
Possible combinations are:
Atmospheric Family | <MAΤP> | Number of internal variance | Link | |
---|---|---|---|---|
Molecular Scattering | S00S | 1 | S0xx.lst | |
Molecular Scattering + Aerosol |
SCτS SDτS |
2 + 2 | SAxx.lst | |
Molecular Absorbing | A00$p$ | 6 | A0xx.lst | |
Molecular Absorbing + Aerosol |
AC$\tau$$p$ AD$\tau$$p$ |
12 + 12 | AAxx.lst | |
Molecular Extinction | E00$p$ | 6 | E0xx.lst | |
Molecular Extinction + Aerosol |
EC$\tau$$p$ ED$\tau$$p$ |
12 + 12 | EAxx.lst | |
No gas | 0C$\tau$S 0D$\tau$S |
4 | 0Axx.lst | |
All | -- | 69 | MATP.lst |
Only 6 bands Sentinel-2A MSI are considered in RAMI4ATM.
<BND> identifier tag | Tag meaning | Priority |
---|---|---|
M02 | Sentinel-2A MSI band 02, Blue band | 1 |
M03 | Sentinel-2A MSI band 03, Green band | 1 |
M04 | Sentinel-2A MSI band 04, Red band | 1 |
M8A | Sentinel-2A MSI band 08a, NIR | 1 |
M11 | Sentinel-2A MSI band 11, SWIR | 2 |
M12 | Sentinel-2A MSI band 12, SWIR | 2 |
The corresponding JSON dotted notation is
scenario.observations.measures.satellite scenario.observations.measures.instrument scenario.observations.measures.band
All optical properties are assumed spectrally invariant within the considered MSI bands.
To calculate the spectral properties for each band we performed the convolution of the extraterrestrial solar spectrum with the spectral response and the reflectance spectrum of soil, leaf or trunks , accordingly to the equation
The MSI spectral responses functions (S2-SRF) $S_\lambda$ were taken from "Sentinel-2 Spectral Response Functions" file.
Illumination angles are described using a RAMI-V compatible convention.
In RAMI4ATM, only 4 illumination conditions are considered, corresponding to different sun zenith angles. Considering the number of different scenarios in RAMI4ATM, it has been decided to prioritise the computation order depending on the SZA.
<zZZZaAA> identifier tag | Value of the solar zenith | Value of the solar azimuth | Priority |
---|---|---|---|
z00a000 | 0.0 | 0.0 | 2 |
z30a000 | 30.0 | 0.0 | 1 |
z60a000 | 60.0 | 0.0 | 3 |
z75a000 | 75.0 | 0.0 | 4 |
The corresponding JSON dotted notation is
scenario.observations.illumination.saa scenario.observations.illumination.sza
Three different measures are taken in consideration: Bi-directional Reflectance Factor, Bi-Hemispherical Reflectance and Hemispherical Directional Reflectance.
Table 6 lists the measurement tags and the links to the corresponding file format description pages. The last column refers to the vertical level at which the measurement will be carried out.
<meas> Identifier tag | Link to Format file description | Level of the measurement |
---|---|---|
bhr | Bi-Hemispherical Reflectance | BOA |
hdrfpp | Hemispherical Directional Reflectance Factor in the principal plane | BOA |
hdrfop | Hemispherical Directional Reflectance Factor in the orthogonal plane | BOA |
brfpp | Bi-directional Reflectance Factor in the principal plane | TOA |
brfop | Bi-directional Reflectance Factor in the orthogonal Plane | TOA |
The corresponding JSON dotted notation is
scenario.observations.measures.measure_type